The present invention relates to a film holder for bite-wing radiographs and having an X-ray cone centering device.
In order to provide an as true as possible print of teeth, i.e. one which is undistorted, it is necessary to position properly an X-ray film located in a holding device and to bring the X-ray cone up to the X-ray film. A film holder having a centering device is known from the U.S. Pat. No. 3,003,062 and is provided to enable all the teeth to be X-rayed. For this purpose the holder is provided with a rotatable shank, in order to be usable on either the right-hand or left-hand side of the mouth, and for either the lower or upper teeth respectively to be exposed. This film holder is intended for a specific type of X-ray cone and, moreover, is intended to be used such that after each exposure only the film is changed and the holder is then re-used. This re-use, however, provides a problem with respect to hygiene since it is difficult for the holder to be sterilized and also such holder may be used only with a certain type of cone. The instruments of the Rinn Corporation, Elgin, Ill., U.S.A., concerned with this U.S. Patent are modified in essential points and have a clamping clip for an X-ray film, a mouthpiece, a metal rod bent at right angles and a ring guided thereon for centering the X-ray cone. Compared with the ebodiments of U.S. Pat. No. 3,003,062, the rotatable shank has been omitted and replaced by a ring functioning as the centering system. Besides the problems relating to hygiene, which result from the repeated application of the instrument, the latter holder has the disadvantage in that it is applicable only to a definite type of X-ray cone.
Also to secure the X-ray film, known discardable film holders made of cardboard or plastic material are used and are either slipped over the X-ray film or resiliently retain such. These X-ray film holders, however, have no device whatsoever to guide and center the X-ray cone so that the dentist is substantially dependent on visual judgement since the cone has applied thereto only a graduation to determine the inclination relative to the floor and such exposures are only possible with patients in the sitting position.